JPS62293501A - Magnetic bias generating device - Google Patents

Abstract

PURPOSE:To attain miniaturization and light weight by providing a permanent magnet having a specific width sliding on a shaft arranged in a gap of an electromagnet in response to the polarity of the electromagnet and moving the permanent magnet so as to apply magnetization processing to full track width of a magnetic disk. CONSTITUTION:The electromagnet 1 is formed so that ends of a magnetic yoke 3 are opposed to each other and the both are of the same pole by an exciting coil 3. A fixed shaft 5 and the permanent magnet 4 magnetized in the side face axial direction supported freely slidably by a bearing member 6 on the shaft 5 are provided to the air gap 8 of the magnet 1. Thus, the magnet 4 is attracted axially in response to the polarity of the ends of the magnet 1 and moved. Thus, the movement of the magnet 4 radiates the magnetic flux thetaof an optional polarity to the processing part of a track of the magnetic disk to magnetize the part. In using a width at a right angle in the sliding direction of the magnet 4 as a track width, the magnetizing processing is applied by the movement of the magnet 4 only without moving a magnetic bias generator. Thus, the miniaturization and light weight are attained for the titled device.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (1) Purpose of the Invention (Field of Industrial Application) The present invention relates to a magnetic bias generation device used in a writing device for a magneto-optical disk storage device. It is.

(Conventional technology) Problems in the prior art will be explained with reference to FIG.

Figure 3 is a conceptual diagram of a conventional magneto-optical disk storage device.The basic function of a magneto-optical disk storage device is the same as that of other magnetic disk storage devices, and there is a magnetic material on the surface of a rotating disk. A magnetic disk on which a thin film is formed is rotated at a constant speed, and a magnetic head disposed close to the magnetic disk magnetizes the magnetic thin film on the magnetic disk to store data. Data is read by detecting the voltage of the magnetic head induced by changes in the magnetic flux of a magnetized thin film of magnetic material.

In the magnetic thin film 100 formed on the surface of the magnetic disk 101 as a storage medium, the area for storing data is l] corresponding to the thickness of a magnetic head (not shown),
It forms a ring whose radius is the distance from the center of rotation of the magnetic disk 101 to the stop position of the magnetic head, and the ring-shaped area: A large amount of data can be stored by forming a large number of tracks concentrically. The matter is well known.

In conventional magnetic disk storage devices, one way to increase storage capacity is to reduce the thickness of the magnetic head to narrow the track width and increase the number of tracks on the surface of the magnetic thin film 100. However, there was a problem in that reducing the thickness of the magnetic head resulted in a decrease in sensitivity.

Magneto-optical disk storage devices were devised to solve this problem and increase track density. In FIG. 3(c), a magnetic bias generator 105 applies a magnetic thin film 100 formed on the surface of a magnetic disk 101.
The magnetic flux 115 from the magnetic thin film 100 acts almost perpendicularly to form magnetic domains 111 indicating magnetic poles on the front and back sides of the magnetic thin film 100.

The polarity of the magnetic domain 111 follows the bias magnetic flux 115 from the magnetic bias generator.

Further, a light beam 114 from the light beam generator 104 is irradiated so as to be focused on the magnetic thin film 100, and the magnetic thin film 100 irradiated with this light beam 114 is
The extremely narrow ``plane'' of the surface is instantaneously heated by the thermal energy of the irradiated light.

This heating causes the magnetic material used in the magnetic disk 101 to exceed the Curie point, causing the existing magnetic poles to disappear and become ready for new magnetization, that is, for storing new data.

The magnetic domain 111, which is the "plane" where the magnetic pole has disappeared, stores data by forming a new magnetic pole with the magnetic flux 115 from the magnetic bias generator 105.

The configuration using the light beam 114 allows heating during irradiation of the focused light to be much smaller than the critical dimension regulated by the thickness of conventional magnetic heads. The width of the surface where magnetism disappears, that is, the magnetic domain 111, is small, and therefore the storage capacity can be increased to a greater extent than that of conventional magnetic disks.

However, despite the above-mentioned performance improvements, the magneto-optical disk storage devices in practical use require a linear motor 106 to move the magnetic bias generator 105 to the track position where predetermined data processing is performed. There have been problems, such as the size of the coil of the magnetic bias generator 105 for generating bias magnetic flux, which hinders miniaturization of the entire device.

(Problems to be Solved by the Invention) The present invention provides a magnetic bias generating device that does not impair storage capacity and can realize a magneto-optical disk storage device with a simple configuration.

(2) Configuration of the Invention (Means for Solving Problems) The magnetic bias generating device of the present invention includes an electromagnet configured such that both opposing end surfaces thereof exhibit the same polarity.

A shaft is disposed so as to straddle the gap formed by the end of the electromagnet, and the shaft is slidably supported by a bearing member.

The side surface is magnetized in the axial direction, and the magnetized surface has a flat plate shape,
A sliding part of the movable part that slides on the shaft and the movable part, comprising a movable part whose main component is a permanent magnet whose width in a direction perpendicular to the sliding direction is at least equivalent to the total track width of the magnetic disk. The electromagnet has a non-circular cross-sectional shape, and a buffer member is arranged and fixed to both ends of the electromagnet or both end faces of the movable part, and the excitation coil of the electromagnet is provided with a recess in the magnetic yoke and wound around the recess, Further, a magnetic shielding plate having a slit with a width equal to or narrower than one of the magnetic pole widths of the permanent magnets is arranged opposite to the magnetized surface of the permanent magnets.

(Function) In the configuration described above, a linear motor is not required to move to a predetermined track position.

In addition to being able to perform predetermined data processing only by applying a signal to a fixed magnetic bias generator, it also brings about effects such as making it possible to downsize the entire device.

(Example) The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a plan view (a) and an enlarged view (b) of an example of a magnetic bias generating device according to the present invention. In this example, two magnetic yokes 2 having a similar structure are arranged, and the magnetic yokes The excitation coil 3, which is wound around the magnetic yoke 2, is excited so that the ends of the magnetic yoke 2 face each other and have the same magnetic polarity.

In the air gap 8 formed by both ends of the magnetic yoke 2, there is a shaft 5 fixed to the air gap 8 so as to straddle the air gap 8, and a shaft 5 is rotatably supported by a bearing member 6, and the side surface of the shaft 5 is polarized in the axial direction. permanent magnet 4
Alternatively, they are arranged as shown in the enlarged view of the main part in FIG.

In the illustrated example where the polarity of the permanent magnet 4 is N on the left side and S on the right side, when the electromagnet is excited so that the end polarity becomes S, the slidable permanent magnet 4 is attracted to the left as shown in the figure. When the input is reversed and the end polarity of the electromagnet becomes N, the permanent magnet 4 is attracted to the right side of the air gap 8.

The above-mentioned moving operation of the permanent magnet 4 brings about a reversal of the magnetic flux Φ irradiated to the corresponding processing portion of the track of the magnetic disk (not shown) located to the side of the approximate center of the air gap 8.

That is, as described above, the axial movement of the permanent magnet 4 generates magnetic flux of arbitrary polarity with respect to the corresponding location on the track of the magnetic disk:
It is configured to irradiate Φ and arbitrarily magnetize the magnetic domains that have been demagnetized by the light beam as described above.

Furthermore, by making the width of the permanent magnet 4 in the direction perpendicular to the sliding direction equal to or larger than all the tracks of the magnetic disk, it is possible to eliminate the need to move the position of the magnetic bias generator for all tracks. , arbitrary magnetization processing can be performed simply by moving the permanent magnet 4. In this example, as shown in the same figure (b), t1 is used to reduce the impact when the permanent magnet 4 collides with the magnetic pole part of the electromagnet 1 during the left-right high-speed reversal operation.
Although the impact members 7 are arranged at both ends of the permanent magnet 4.

This may be arranged and fixed at the end of the electromagnet 1.

The excitation coil 3 wound around the magnetic yoke 2 can be wound at any position, or by configuring the winding part of the magnetic yoke 2 in a concave shape, the thickness of the entire device of the excitation coil 3 can be reduced. There are also ways to reduce the impact on dimensions.

Furthermore, a magnetic shielding plate 9 is shown by a dotted line in FIG. 1, and the purpose of the slit 10 formed in the shielding plate 9 is to converge the magnetic flux Φ irradiated from the surface of the permanent magnet 4 only to a predetermined polarity side. It will be attached to.

Further, FIG. 2 is a plan view of an example in which the magnetic yoke 2 is integrated.

(3) Effects of the Invention Since the magnetic bias generating device of the present invention has the above-described configuration, it is possible to obtain bias magnetic flux for all tracks l of the magnetic disk simply by alternately exciting the excitation coil of the electromagnet. In addition, the mass of the movable parts can be reduced, the configuration can be simplified, and the device can be made smaller and lighter.

[Brief explanation of drawings]

FIG. 1 is a plan view (a) and an enlarged sectional view (b) of the main part showing an example of the present invention, FIG. 2 is another upside down plan view, and FIG. 3 is a conventional magneto-optical disk. Conceptual diagram of a storage device, including a plan view (a), a front view (b), and an enlarged view of main parts (c)
It is. Explanation of symbols 1: Electromagnet, 2: Magnetic yoke, 3: Exciting coil,
4. Permanent magnet, 5. Shaft, 6. Bearing member, 7. Buffer member, 8. Air gap, 9. Magnetic shielding plate, 10. Slit. 100...Magnetic thin film, 101...Magnetic disk, 10
2... Disk drive electric motor, 103... Board of the entire device, 104... Light beam generator, 105... Magnetic bias generator, 106... Linear motor for moving the magnetic bias generator, 111... Magnetic domain, 114...Light beam, 115...Bias magnetic flux. Patent applicant Nippon Servo Co., Ltd. Figure 1

Claims (7)

[Claims] (1) An electromagnet consisting of a magnetic yoke and an excitation coil wound around the yoke, the ends of which are opposite to each other and both exhibit the same polarity, and both ends of the electromagnet are formed. A movable part that is slidably supported on the shaft and whose main members are permanent magnets that are alternately magnetized in the axial direction of the side surfaces of the shaft. Magnetic bias generator. (2) The magnetized surface of the permanent magnet has a flat plate shape, and the width in the direction perpendicular to the sliding direction is at least equivalent to the total track width of the magnetic disk. The magnetic bias generating device according to claim 1, wherein the magnetic bias generating device is mounted and pivotally supported. (3) The magnetic bias generating device according to claims 1 and 2, characterized in that the sliding portion of the shaft and the movable portion that slides on the shaft has a non-circular cross-sectional shape. (4) A magnetic bias generating device according to any one of claims 1 to 3, characterized in that buffer members are provided and fixed to both ends of the electromagnet. (5) A magnetic bias generating device according to any one of claims 1 to 3, characterized in that buffer members are arranged and fixed to both end faces of the movable part. (6) A magnetic bias generating device according to any one of claims 1 to 5, characterized in that a recess is provided in the magnetic yoke forming the electromagnet, and an excitation coil is wound around the recess. (7) A claim characterized in that a magnetic shielding plate in which a slit with a width equal to or narrower than one of the magnetic poles of the permanent magnet is provided is provided so as to face the magnetized surface of the permanent magnet. The magnetic bias generator according to items 1 to 6.